Electromagnetic probers which perform an exploratory survey by radiating electromagnetic radiation from an antenna, receiving an echo from an object and analyzing the echo have conventionally been developed, and employed for survey of buried objects such as buried pipes and landmines. Unfortunately, none of the conventional electromagnetic probers have the function of measuring a dielectric constant at each depth level in the ground.
However, it is necessary to measure dielectric constants in an electromagnetic wave propagation medium on a case-by-case basis for the determination of a depth at which an object such as a buried pipe or a landmine to be surveyed is present, because the propagation speed of the electromagnetic radiation differs depending on the dielectric constant in the propagation medium.
There is also known a technique for determining the depth of an object to be surveyed by employing a synthetic aperture radar method. However, the exploratory survey employing the synthetic aperture method is difficult for unskilled persons, so that everybody cannot easily carry out the survey.
It is therefore an object of the present invention to permit even an unskilled person to easily measure a dielectric constant at each depth level in a medium to determine a depth at which an object to be surveyed is present without employing the synthetic aperture method.